This invention relates to intermediates for .beta.-lactam antibiotic compounds. In particular, it relates to chiral azetidinone intermediates useful in the preparation of .beta.-lactam antibiotics.
The ketene-imine cycloaddition process for the preparation of azetidinones has been previously studied. For example, D. A. Evans and E. B. Sjogren, Tetrahedron Letters, Vol. 26, No. 32, pp. 3783-3786, ibid pp. 3787-3790, and Ikota et al., Heterocycles, 1984, 22, 2227, have reported on the asymmetric preparation of azetidinones by the ketene-imine cycloaddition. Such studies are directed to the preparation of newer antibiotic substances not obtainable by natural means such as by fermentation. Intermediates having the correct chirality for the desired antibiotic would be valuable compounds useful in the preparation in non-classical .beta.-lactam antibiotics.